It is well-known that in a conventional core-shooting machine the corebox is located on the so-called working table, which table is hydraulically provided with upward and downward movement. The blowing cartridge is in turn provided on the corebox, loaded with the measure of sand and binding additives required to fill the box and obtain the desired core. The blowing head (not shown) is provided on the blowing cartridge to cause the release of the air-blast which reaches into the cartridge and drives the sand from the same into the corebox, once the three parts, namely corebox-cartridge-blowing head are tightly coupled when the air is released.
Depending on whether the process is in a hot or a cold box, heat is provided to the boxes or else they are gassed in order to cause the binding material to be polymerized and hence the core produced to be hardened, thereupon to be removed from the box.
In the so-called self-setting process, the sand is mixed by additives that are able to cause self-setting within a short period of time (one second) and the casting process begins almost in the actual cartridge, whence if the release of the air-blast is delayed only slightly the outlet of the cartridge may be blocked and the discharge of the sand impaired or at least is not fully effected.
In the above conventional shooters, between the cartridge carrying the measure of sand and the corebox, the so-called blowing plate is provided, fitted with a number of nozzles for the sand to reach the box through selected points, in accordance with the geometric and dimensional characteristics and the complexity of the core to be made, viz. the inner voluble of the corebox which must be uniformly filled with sand, reaching all its corners. Each blowing plate will therefore be studied for a given corebox so that a change of box will entail a change of blowing plate, which poses no serious problem in mass productions or large series, for the box changes take place over long time spreads.
However, when in small productions, short series, the boxes are changed frequently and therefore so is the blowing plate, which means that a considerable amount of production time is wasted due to the handling operations required.
Furthermore, when complex or sizeable cores are to be obtained in a process known as self-setting, the conventional core-shooting machines can prove inefficient, either because they are not able to fully and evenly fill the corebox, or because part of the sand remains in the cartridge because the setting process shall have begun therein, and the air-blast released shall have been insufficient to drive the mixture entirely.